1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly, to a backlight unit for the LCD.
2. Description of the Related Art
Recently, much effort has been made to study and develop various types of flat panel display, such as a liquid crystal display (LCD) device, a field emission display (FED) device, an electro-luminescence display (ELD) device, a plasma display panel (PDP), etc. Among these flat panel display devices, the LCD device has attracted considerable attention because of its high resolution, light weight, thin profile, compact size and low power consumption.
The LCD controls a light transmittance of a liquid crystal material to thereby display a picture. To this end, the LCD includes an LCD module having an LCD panel, a driving circuitry for driving the LCD module, and a case. The LCD panel has liquid crystal cells arranged in a matrix form between two glass substrates, a backlight unit for irradiating light onto the LCD panel, and a casing. Hereinafter, a related art LCD device will be described with reference to the accompanying drawings as follows.
FIG. 1 is a front view illustrating a related art LCD device after an assembly, FIG. 2 is a rear view of the LCD device of FIG. 1, FIG. 3 is a sectional view illustrating the LCD device taken along the line I-I′ in FIG. 1, and FIG. 4 is a perspective view illustrating a bottom cover of the LCD device shown in FIG. 3.
As shown in FIGS. 1 to 4, the related art LCD device includes an LCD panel 10, a top case 1 installed at an upper part of the LCD panel 10, and a backlight unit that is installed at a lower part of the LCD panel 10 to irradiate light to a rear surface of the LCD panel 10. A liquid crystal material is injected between two substrates (not shown) to display a picture, and the top case 1 encases the LCD panel 10 and the backlight unit.
The backlight unit includes a main supporter 3, a bottom cover 2, a lamp 6 that irradiates light to the rear surface of the LCD panel 10, and a light guide plate 8 installed along a side surface of the lamp 6. The main supporter 3 is installed at the lower part of the LCD panel 10 and is formed with a mounting space penetrated from an upper surface to a lower surface in order to mount the LCD panel 10 and the lamp 6 to fix them. Further, the bottom cover 2, which protects the lamp 6 and prevents a leakage of light, is installed at a lower part of the main supporter 3. The main supporter 3 is generally formed of a plastic material. The bottom cover 2 is formed of a metal material, such as aluminum or the like, which has a better heat conductivity than the plastic material. Moreover, a lamp housing 7 is installed to surround the lamp 6.
The light guide plate 8 is installed along the side surface of the lamp 6 to transform light irradiated from the lamp 6 into a surface light to uniformly supply the surface light to the LCD panel 10. A reflection plate 5 is arranged at a lower part of the light guide plate 8 to re-reflect light leaked to an opposition direction of the LCD panel 10. The lamp housing 7 reflects light radiated from the lamp 6 to the light guide plate 8.
An optical sheet 4 includes a diffusion sheet 43, a prism sheet 42 and a protection sheet 41, which are sequentially located at the upper part of the light guide plate 8. Among these sheets, the diffusion sheet 43 diffuses the light from the light guide plate 8 to radiate a uniform light, the prism sheet 42 concentrates the light diffused from the diffusion sheet 43, and the protection sheet 41 protects the prism sheet 42 and diffuses an incident light to radiate a uniform light.
As shown in FIG. 3, the bottom cover 2 is engaged with the main supporter 3. As shown in FIG. 4, the bottom cover 2 is formed in an integration structure, and is formed with four bent parts 21 at each side surface thereof. In each of the bent parts 21, a plurality of engaged holes 21a are formed corresponding to engaging protrusions (not shown) formed in the main supporter 3. The engaging protrusions formed in the main supporter 3 are engaged in the respective engaged holes 21a, thereby securing the main supporter 3 and the bottom cover 2.
However, since the bottom cover 2 is formed in the integration structure, costs for manufacturing the related art LCD device are increased. Moreover, it is time-consuming to develop a mold and to perform management control.